Russian President Dmitry Medvedev and his U.S. counterpart Barack Obama held a telephone conversation late Monday over the tragic twin blasts at Moscow metro stations.

Obama conveyed sympathy and support to Russia concerning the blasts, said the Kremlin on its website.

The U.S. president said hopefully the Russian people would know that the American people fully support their fight against terrorism and are ready to do everything possible to defeat this evil and punish the guilty.

Medvedev, for his part, thanked Obama for his support. He also stressed that fight on terrorism was one of the most urgent cooperative fields between Moscow and Washington.

"We must work together to cooperate to make sure that the terrorist threat has not occupied the entire planet," said Medvedev.

Earlier in a written statement, Obama said: "The American people stand united with the people of Russia in opposition to violent extremism and heinous terrorist attacks that demonstrate such disregard for human life, and we condemn these outrageous acts."

The two presidents also held detailed discussions over their upcoming meeting in Prague to sign a new treaty on strategic offensive arms and other issues.

The twin blasts occurred on Monday morning, killing at least 38 people and injuring more than 64. The first took place at 7:52 a.m. local time (0352 GMT) at the Lubyanka station and the second bomb detonated some 40 minutes later at the nearby Cultural Park station.

The blasts were confirmed as having been set off by two female suicide bombers who probably were linked to terrorist groups in the North Caucasus.